Acoustic emission toughness testing for PDC, PCBN, or other hard or superhard material inserts

ABSTRACT

An acoustic emissions testing device includes a testing sample, an acoustic sensor communicably coupled to the testing sample, and a load that is exerted on the sample. The acoustic sensor detects one or more acoustic events occurring within the sample. The acoustic sensor transmits data to a data recorder, which includes a processor and storage medium for executing instructions provided by a software residing within the storage medium. Upon executing the instructions on the transmitted data, the toughness of the sample is objectively determined and can be ranked comparatively to the toughness of other samples. The instructions provide for categorizing the data into possible acoustic event points and background data points, interpolating a background noise curve, determining the actual acoustic event points, and calculating the area under each actual acoustic event point.

RELATED APPLICATIONS

The present application is related to U.S. patent application Ser. No.12/754,784, entitled “Acoustic Emission Toughness Testing For PDC, PCBN,Or Other Hard Or Superhard Material Inserts” and filed on Apr. 6, 2010,which is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates generally to a method, apparatus, andsoftware for determining the intrinsic strength, or toughness, of hardor superhard components; and more particularly, to a method, apparatus,and software for determining the intrinsic strength, or toughness, ofhard or superhard components using acoustic emissions.

BACKGROUND

FIG. 1 shows a superhard component 100 that is insertable within adownhole tool (not shown), such as a drill bit or a reamer, inaccordance with an exemplary embodiment of the invention. One example ofa superhard component 100 is a cutting element 100, or cutter or insert,for rock bits, as shown in FIG. 1. However, the superhard component 100can be formed into other structures based upon the application that itis to be used in. The cutting element 100 typically includes a substrate110 having a contact face 115 and a cutting table 120. The cutting table120 is fabricated using an ultra hard layer which is bonded to thecontact face 115 by a sintering process according to one example.According to some examples, the substrate 110 is generally made fromtungsten carbide-cobalt, or tungsten carbide, while the cutting table120 is formed using a polycrystalline ultra hard material layer, such aspolycrystalline diamond (“PCD”) or polycrystalline cubic boron nitride(“PCBN”). These cutting elements 100 are fabricated according toprocesses and materials known to persons having ordinary skill in theart. Although the cutting table 120 is shown having a substantiallyplanar outer surface, the cutting table 120 can have alternative shapedouter surfaces, such as dome-shaped, concave-shaped, or other non-planarshaped outer surfaces, in other embodiments. Although some exemplaryformulations for the cutting element 100 have been provided, otherformulations and structures known to people having ordinary skill in theart can be used depending upon the application. Although rock drillingis one application that the superhard component 100 can be used in andwhich is described hereinbelow, the superhard component 100 can be usedin various other applications including, but not limited to, machining,woodworking, and quarrying.

Different PCD, PCBN, hard, and superhard material grades are availablefor the cutters 100 to be used in various applications, such as drillingdifferent rock formations using different drill bit designs or machiningdifferent metals or materials. Common problems associated with thesecutters 100 include chipping, spalling, partial fracturing, cracking,and/or flaking of the cutting table 120 during use. These problemsresult in the early failure of the cutting table 120 and/or thesubstrate 110. Typically, high magnitude stresses generated on thecutting table 120 at the region where the cutting table 120 makescontact with earthen formations during drilling can cause theseproblems. These problems increase the cost of drilling due to costsassociated with repair, production downtime, and labor costs. Thus, anend-user, such as a bit designer or a field application engineer,chooses the best performing grade of the cutter 100 for any givendrilling or machining task to reduce these common problems fromoccurring. For example, the end-user selects an appropriate cutter 100by balancing the wear resistance and the impact resistance of the cutter100, as determined using conventional methods. Typically, theinformation available to the end-user for selecting the appropriategrade cutter 100 for a particular application is derived from historicaldata records that show performance of different grades of PCD, PCBN,hard, or superhard material in specific areas and/or from laboratoryfunctional tests which attempt to mimic various drilling or machiningconditions while testing different cutters 100. There are currently twomain categories of laboratory functional testing that are used in thedrilling industry. These tests are the wear abrasion test and the impacttest.

Superhard components 100, which include polycrystalline diamond compact(“PDC”) cutters 100, have been tested for abrasive wear resistancethrough the use of two conventional testing methods. The PDC cutter 100includes the cutting table 120 fabricated from PCD. FIG. 2 shows a lathe200 for testing abrasive wear resistance using a conventional granitelog test. Although one exemplary apparatus configuration for the lathe200 is provided, other apparatus configurations known to people havingordinary skill in the art can be used without departing from the scopeand spirit of the exemplary embodiment.

Referring to FIG. 2, the lathe 200 includes a chuck 210, a tailstock220, and a tool post 230 positioned between the chuck 210 and thetailstock 220. A target cylinder 250 has a first end 252, a second end254, and a sidewall 258 extending from the first end 252 to the secondend 254. According to the conventional granite log test, sidewall 258 isan exposed surface 259 which makes contact with the superhard component100 during the test. The first end 252 is coupled to the chuck 210,while the second end 254 is coupled to the tailstock 220. The chuck 210is configured to rotate, thereby causing the target cylinder 250 to alsorotate along a central axis 256 of the target cylinder 250. Thetailstock 220 is configured to hold the second end 254 in place whilethe target cylinder 250 rotates. The target cylinder 250 is fabricatedfrom a single uniform material, which is typically granite. However,other rock types have been used for the target cylinder 250, whichincludes, but is not limited to, Jackforck sandstone, Indiana limestone,Berea sandstone, Carthage marble, Champlain black marble, Berkleygranite, Sierra white granite, Texas pink granite, and Georgia graygranite.

The PDC cutter 100 is fitted to the lathe's tool post 230 so that thePDC cutter 100 makes contact with the target cylinder's 250 exposedsurface 259 and drawn back and forth across the exposed surface 259. Thetool post 230 has an inward feed rate on the target cylinder 250. Theabrasive wear resistance for the PDC cutter 100 is determined as a wearratio, which is defined as the volume of target cylinder 250 that isremoved to the volume of the PDC cutter 100 that is removed.Alternatively, instead of measuring volume, the distance that the PDCcutter 100 travels across the target cylinder 250 can be measured andused to quantify the abrasive wear resistance for the PDC cutter 100.Alternatively, other methods known to persons having ordinary skill inthe art can be used to determine the wear resistance using the granitelog test. Operation and construction of the lathe 200 is known to peoplehaving ordinary skill in the art. Descriptions of this type of test isfound in the Eaton, B. A., Bower, Jr., A. B., and Martis, J. A.“Manufactured Diamond Cutters Used In Drilling Bits.” Journal ofPetroleum Technology, May 1975, 543-551. Society of Petroleum Engineerspaper 5074-PA, which was published in the Journal of PetroleumTechnology in May 1975, and also found in Maurer, William C., AdvancedDrilling Techniques, Chapter 22, The Petroleum Publishing Company, 1980,pp. 541-591, which is incorporated by reference herein.

FIG. 3 shows a vertical boring mill 300 for testing abrasive wearresistance using a vertical boring mill (“VBM”) test or vertical turretlathe (“VTL”) test. Although one exemplary apparatus configuration forthe VBM 300 is provided, other apparatus configurations can be usedwithout departing from the scope and spirit of the exemplary embodiment.The vertical boring mill 300 includes a rotating table 310 and a toolholder 320 positioned above the rotating table 310. A target cylinder350 has a first end 352, a second end 354, and a sidewall 358 extendingfrom the first end 352 to the second end 354. According to theconventional VBM test, second end 354 is an exposed surface 359 whichmakes contact with a superhard component 100 during the test. The targetcylinder 350 is typically about thirty inches to about sixty inches indiameter; however, this diameter can be greater or smaller.

The first end 352 is mounted on the lower rotating table 310 of the VBM300, thereby having the exposed surface 359 face the tool holder 320.The PDC cutter 100 is mounted in the tool holder 320 above the targetcylinder's exposed surface 359 and makes contact with the exposedsurface 359. The target cylinder 350 is rotated as the tool holder 320cycles the PDC cutter 100 from the center of the target cylinder'sexposed surface 359 out to its edge and back again to the center of thetarget cylinder's exposed surface 359. The tool holder 320 has apredetermined downward feed rate. The VBM method allows for higher loadsto be placed on the PDC cutter 100 and the larger target cylinder 350provides for a greater rock volume for the PDC cutter 100 to act on. Thetarget cylinder 350 is typically fabricated from granite; however, thetarget cylinder can be fabricated from other materials that include, butis not limited to, Jackforck sandstone, Indiana limestone, Bereasandstone, Carthage marble, Champlain black marble, Berkley granite,Sierra white granite, Texas pink granite, and Georgia gray granite.

The abrasive wear resistance for the PDC cutter 100 is determined as awear ratio, which is defined as the volume of target cylinder 350 thatis removed to the volume of the PDC cutter 100 that is removed.Alternatively, instead of measuring volume, the distance that the PDCcutter 100 travels across the target cylinder 350 can be measured andused to quantify the abrasive wear resistance for the PDC cutter 100.Alternatively, other methods known to persons having ordinary skill inthe art can be used to determine the wear resistance using the VBM test.Operation and construction of the VBM 300 is known to people havingordinary skill in the art. A description for this type of testing can befound in Bertagnolli, Ken and Vale, Roger, “Understanding andControlling Residual Stresses in Thick Polycrystalline Diamond Cuttersfor Enhanced Durability,” US Synthetic Corporation, 2000, which isincorporated by reference in its entirety herein.

In addition to testing for abrasive wear resistance, PDC cutters 100also can be tested for resistance to impact loading. FIG. 4 shows a droptower apparatus 400 for testing impact resistance of superhardcomponents using a “drop hammer” test where a metal weight 450 issuspended above and dropped onto the cutter 100. The “drop hammer” testattempts to emulate the type of loading that can be encountered when thePDC cutter 100 transitions from one formation to another or experienceslateral and axial vibrations. Results from the impact testing allows forranking different cutters based upon their impact strength; however,these ranking do not allow for predictions to be made according to howthe cutters 100 will perform in the actual field.

Referring to FIG. 4, the drop tower apparatus 400 includes a superhardcomponent 100, such as a PDC cutter, a target fixture 420, and a strikeplate 450 positioned above the superhard component 100. The PDC cutter100 is locked into the target fixture 420. The strike plate 450, orweight, is typically fabricated from steel and is positioned above thePDC cutter 100. However, the strike plate 450 can be fabricated fromalternative materials known to persons having ordinary skill in the art.The PDC cutter 100 is typically held at a backrake angle 415 with thediamond table 120 of the PDC cutter 100 angled upward towards the strikeplate 450. The range for the backrake angle 415 is known to peoplehaving ordinary skill in the art.

The strike plate 450 is repeatedly dropped down on the edge of the PDCcutter 100 until the edge of the PDC cutter 100 breaks away or spallsoff. These tests are also referred to as “side impact” tests because thestrike plate 450 impacts an exposed edge of the diamond table 120.Failures typically appear in either the diamond table 120 or at thecontact face 115 between the diamond table 120 and the carbide substrate110. The “drop hammer” test is very sensitive to the edge geometry ofthe diamond table 120. If the table 120 is slightly chamfered, the testresults can be altered considerably. The total energy, expressed inJoules, expended to make the initial fracture in the diamond table 120is recorded. For more highly impact resistant cutters 100, the strikeplate 450 can be dropped according to a preset plan from increasingheights to impart greater impact energy on the cutter 100 to achievefailure. However, this “drop hammer” test embodies drawbacks in thatthis method requires that many cutters 100 be tested to achieve a validstatistical sampling that can compare the relative impact resistance ofone cutter type to another cutter type. The test is inadequate inproviding results that reflect the true impact resistance of the entirecutter 100 as it would see impact loads in a downhole environment. Thetest exhibits a static impact effect whereas the true impact is dynamic.The number of impacts per second can be as high as 100 hertz (“Hz”).Also, the amount of damage to the cutter is subjectively evaluated bysomeone with a trained eye and is compared to damages incurred by othercutters.

While the results for different wear tests available in the market havegenerally a reasonable degree of agreement with the actual fieldperformance, the same is not the case for the results of conventionalimpact tests. Although there is some degree of correlation between theresults of conventional impact tests and actual field performance, thescattering of the data is usually very large, thereby causingpredictions on how cutters will behave in actual field performance to bedifficult and/or inaccurate. Also, many fractures occurring within thecutter are not detected using these conventional tests and therefore goundetected when evaluating the toughness of the cutter.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and aspects of the invention are bestunderstood with reference to the following description of certainexemplary embodiments, when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 shows a superhard component that is insertable within a downholetool in accordance with an exemplary embodiment of the invention;

FIG. 2 shows a lathe for testing abrasive wear resistance using aconventional granite log test;

FIG. 3 shows a vertical boring mill for testing abrasive wear resistanceusing a vertical boring mill test or vertical turret lathe test;

FIG. 4 shows a drop tower apparatus for testing impact resistance ofsuperhard components using a “drop hammer” test;

FIG. 5 shows a perspective view of an acoustic emission testing systemin accordance with an exemplary embodiment of the present invention;

FIG. 6 shows a cross-sectional view of the acoustic emission testingdevice of FIG. 5 in accordance with an exemplary embodiment of thepresent invention;

FIG. 7 shows a perspective view of a cutter holder, as shown in FIG. 5,in accordance with an exemplary embodiment of the present invention;

FIG. 8 shows a perspective view of the acoustic emission testing deviceof FIG. 5 with the indenter being removed from the cutter holder inaccordance with an exemplary embodiment of the present invention;

FIG. 9 shows a perspective view of an acoustic emission testing systemin accordance with an alternative exemplary embodiment of the presentinvention;

FIG. 10 shows a schematic block diagram of a data recorder of FIG. 5 inaccordance with an exemplary embodiment;

FIG. 11 shows a graphical cutter acoustic emission and loadingrepresentation for a cutter experiencing a load of up to about twokilonewtons in accordance with an exemplary embodiment of the presentinvention;

FIG. 12 shows a graphical cutter acoustic emission and loadingrepresentation for a cutter experiencing a load of up to about fivekilonewtons in accordance with an exemplary embodiment of the presentinvention;

FIG. 13 shows a graphical cutter acoustic emission and loadingrepresentation for a cutter experiencing a load of up to about thirtykilonewtons in accordance with an exemplary embodiment of the presentinvention;

FIG. 14 shows a graphical cutter acoustic emission and loadingrepresentation for a cutter experiencing a load of up to about fortykilonewtons in accordance with an exemplary embodiment of the presentinvention;

FIG. 15A shows a graphical cutter acoustic emission and loadingrepresentation for a cutter manufacturer #1 cutter sample #1 cutter typeexperiencing a load of up to about forty-five kilonewtons in accordancewith an exemplary embodiment of the present invention;

FIG. 15B shows a graphical cutter acoustic emission and loadingrepresentation for a cutter manufacturer #2 cutter sample #2 cutter typeexperiencing a load of up to about thirty kilonewtons in accordance withan exemplary embodiment of the present invention;

FIG. 16 illustrates a flowchart of a method for analyzing data pointsreceived from the acoustic sensor, wherein the method includes a loopone method and a loop two method in accordance with an exemplaryembodiment of the present invention;

FIG. 17 illustrates a detailed flowchart of the loop one method of FIG.16 in accordance with an exemplary embodiment of the present invention;

FIG. 18 illustrates a detailed flowchart of the loop two method of FIG.16 in accordance with an exemplary embodiment of the present invention;

FIG. 19 shows a graphical cutter acoustic emission representation for acutter experiencing a load in accordance with an exemplary embodiment ofthe present invention;

FIG. 20 shows a magnified view of a portion of a graphical cutteracoustic emission representation for a cutter experiencing a load inaccordance with an exemplary embodiment of the present invention;

FIG. 21 shows a cumulative distribution representation for each actualacoustic event in accordance with an exemplary embodiment of the presentinvention; and

FIG. 22 shows a block diagram of the processor of FIG. 10 in accordancewith an exemplary embodiment.

The drawings illustrate only exemplary embodiments of the invention andare therefore not to be considered limiting of its scope, as theinvention may admit to other equally effective embodiments.

BRIEF DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present invention is directed to a method, apparatus, and softwarefor determining the intrinsic strength, or toughness, of hard orsuperhard components using acoustic emissions. Although the descriptionof exemplary embodiments is provided below in conjunction with a PDCcutter, alternate embodiments of the invention may be applicable toother types of hard or superhard components including, but not limitedto, PCBN cutters or other hard or superhard components known or not yetknown to persons having ordinary skill in the art. For example, the hardor superhard components include cemented tungsten carbide, siliconcarbide, tungsten carbide matrix coupons, ceramics, or chemical vapordeposition (“CVD”) coated inserts.

The invention is better understood by reading the following descriptionof non-limiting, exemplary embodiments with reference to the attacheddrawings, wherein like parts of each of the figures are identified bylike reference characters, and which are briefly described as follows.FIG. 5 shows a perspective view of an acoustic emission testing system500 in accordance with an exemplary embodiment of the present invention.FIG. 6 shows a cross-sectional view of the acoustic emission testingdevice 505 of FIG. 5 in accordance with an exemplary embodiment of thepresent invention. Referring to FIGS. 5 and 6, the acoustic emissiontesting system 500 includes an acoustic emission testing device 505communicably coupled to a data recorder 590. The acoustic emissiontesting device 505 includes a cutter holder 510, the cutter 100, anindenter 550, and an acoustic sensor 570. In certain embodiments,however, the cutter holder 510 is optional.

FIG. 7 shows a perspective view of the cutter holder 510 in accordancewith an exemplary embodiment of the present invention. Referring toFIGS. 5, 6, and 7, the cutter holder 510 includes first surface 712, asecond surface 714, and a side surface 716. The first surface 712 isdisposed in a plane that is substantially parallel to the plane that thesecond surface 714 is disposed. The side surface 716 extends from thefirst surface 712 to the second surface 714. According to some exemplaryembodiments, the side surface 716 is substantially perpendicular to atleast one of the first surface 712 and the second surface 714. Accordingto alternative exemplary embodiments, the side surface 716 is notsubstantially perpendicular to either the first surface 712 or thesecond surface 714. The cutter holder 510 is fabricated from steel;however, according to other exemplary embodiments, the cutter holder 510is fabricated from any metal, wood, or other suitable material known topeople having ordinary skill in the art that is capable of withstandinga load 580, which is described in further detail below, that is to beapplied. The load 580 can range from about zero kilonewtons to aboutseventy kilonewtons. In certain exemplary embodiments, the suitablematerial is capable of being machined or molded and is capable ofpropagating sound. In certain exemplary embodiments, the suitablematerial is capable of propagating sound at a speed of about1/kilometers per second or higher.

The cutter holder 510 is shaped in a substantially cylindrical shape,wherein the first surface 712 is substantially circular shaped, thesecond surface is substantially circular shaped, and the side surface716 is substantially arcuate shaped. However, the side surface 716includes a coupling portion 730, which is substantially planar, orflat-surfaced, and extends from the first surface 712 to the secondsurface 714. The coupling portion 730 provides a surface for couplingthe acoustic sensor 570 to the cutter holder 510. In certain exemplaryembodiments, the coupling portion 730 does not extend the entire lengthfrom the first surface 712 to the second surface 714. In some exemplaryembodiments, the acoustic sensor 570 is sized such that the acousticsensor 570 is able to be coupled to the side surface 716 that is arcuateshaped. Thus, the coupling portion 730 is optional in those exemplaryembodiments. Although one exemplary shape is provided for the cutterholder 510, the cutter holder 510 can be shaped into any other geometricor non-geometric shape, such as square shaped cylinder or triangularshaped cylinder, without departing from the scope and spirit of theexemplary embodiment.

A cavity 720 is formed within the cutter holder 510 and is sized toreceive the cutter 100, which is further described below. The cavity 720is sized slightly larger in diameter than the diameter of the cutter100, thereby allowing the cutter 100 to easily and freely fit within thecavity 720. The cavity 720 extends from the first surface 712 towardsthe second surface 714, but does not reach the second surface 714. Inother exemplary embodiments, the cavity 720 extends from the firstsurface 712 to the second surface 714 and proceeds through the cutterholder 510, thereby forming a hole within the cutter holder 510. Thecavity 720 is circular in shape, but is any other geometric ornon-geometric shape in other exemplary embodiments. The cavity 720 isformed by machining the cutter holder 510 or molding the cutter holder510 to have the cavity 720 formed therein. Alternatively, the cavity 720is formed using other methods known to people having ordinary skill inthe art. In certain exemplary embodiments, the cavity 720 is formed in amanner to ensure that the cutter 100 is properly aligned in the samemanner each time the cutter 100 is inserted within the cavity 720.

The cutter 100 has been previously described with respect to FIG. 1 andis applicable to the exemplary embodiments. Briefly, the cutter 100includes the substrate 110 and the cutter table 120, which is formed orcoupled to the top of the substrate 110. In the exemplary embodiment,the cutter table 120 is formed from PCD, but alternative exemplaryembodiments have the cutter table 120 fabricated from other hard orsuperhard materials, such as PCBN, without departing from the scope andspirit of the exemplary embodiment. Although cutter 100 has a planarcutter table 120, or is flat-faced, the cutter table 120 can be domeshaped, concave shaped, or any other shape known to people havingordinary skill in the art.

The cutter 100 includes finished and/or grounded cutters as well as“raw” cutters. “Raw” cutters are unfinished and are cutters that aretypically available right out of a pressing cell. Embodiments of thepresent invention allow testing of both these cutter types. Since cuttermanufacturers are able to test “raw” cutters in accordance withembodiments of the present invention, cutter manufacturers are able toinsure that they are meeting specification early in a cutter productionrun. If cutter manufacturers determine that the “raw” cutters 100 arenot meeting appropriate specifications, they are able to make thenecessary changes in their operating parameters to get “good” cuttersbefore continuing on with the cutter production run. Additionally, “raw”cutters are capable of being tested at a lower kilonewton level, orload, to insure that the “raw” cutters are not cracking under the givenload. If cracks are occurring during the testing of the “raw” cutters,cutter manufacturers can forgo the additional expenses associated withfinishing and grinding these “raw” cutters; thereby saving unnecessarycost expenditures. Hence, each “raw” cutter is capable of being testedthrough the acoustic emission testing system 500 using lower load levelsto insure that the cutters 100 are “good” cutters.

Referring to FIG. 6, the cutter 100 is inserted within the cavity 720 ofthe cutter holder 510. The cutter 100 is oriented within the cavity 720so that the cutter table 120 is facing towards the first surface 712, oraway from the second surface 714. According to this exemplaryembodiment, the entire cutter 100 is inserted within the cavity 720.However, in alternative exemplary embodiments, a portion of the cutter100, which includes the entire substrate 110, is completely insertedwithin the cavity 720. Thus, in these alternative exemplary embodiments,at least a portion of the cutter table 120 is not inserted within thecavity 720. Once the cutter 100 has been inserted within the cavity 720,an air gap 610 is formed between the outer perimeter of the cutter 100and the outer surface of the cavity 720. According to certain exemplaryembodiments, a lubricant 620 is applied to the outer perimeter of thecutter 100 or placed within the cavity 720. In these exemplaryembodiments, once the cutter 100 is placed within the cavity 720, thelubricant 620 fills at least a portion of the air gap 610 such that thelubricant 620 adheres to both the outer surface of the cavity 720 andthe outer perimeter of the cutter 100 and occupies the portion of theair gap 610 therebetween. In other exemplary embodiments, the lubricant620 is placed at least between the bottom surface of the cavity 720 andthe base of the cutter 100. The lubricant 620 improves acoustictransmission between the cutter 100 and the acoustic sensor 570. Thelubricant 620 is a gel, such as an ultrasound gel, according to someexemplary embodiments. However, in alternative exemplary embodiments,other materials can be used as the lubricant 620, which includes, but isnot limited to, oils, grease, and lotions. These materials are capableof being spread, adhering to surfaces, and not rapidly drying out.Although the cutter 100 is described as being used in this exemplaryembodiment, other hard or superhard materials that desire a toughnesstesting can be used in lieu of the cutter 100.

Referring back to FIGS. 5 and 6, the indenter 550 is dome shaped at afirst end 650 and has a planar surface at a second end 652. The indenter550 is fabricated to be tougher than the cutter 100 so that once load580 is applied to the indenter 550, it is the cutter 100 that is damagedand not the indenter 550. For example, the indenter 550 is fabricatedfrom tungsten carbide-cobalt; however, other materials known to thosehaving ordinary skill in the art can be used to fabricate the indenter550. In certain exemplary embodiments, the cobalt content of theindenter 550 ranges from about six percent to about twenty percent. Incertain exemplary embodiments, the cobalt content of the indenter 550 isgreater than the cobalt content of the cutter table 120 of the cutter100. Additionally, in certain exemplary embodiments, a PCD layer isformed or mounted onto the first end 650 of the indenter 550. In theseembodiments, the cobalt content of the PCD layer of the indenter 550 isgreater than the cobalt content of the cutter table 120 of the cutter100. Also, in these exemplary embodiments, the cobalt content of the PCDlayer of the indenter 550 ranges from about six percent to about twentypercent. Although cobalt is used in these exemplary embodiments to makethe indenter tougher than the cutter 100, other components known topeople having ordinary skill in the art can be used in alternativeexemplary embodiments.

The indenter 550 is sized to fit within the cavity 720 so that it makescontact with the cutter 100. In certain exemplary embodiments, theperimeter of the indenter 550 is sized substantially similar to theperimeter of the cavity 720. However, in the exemplary embodiments whereat least a portion of the cutter table 120 is not within the cavity 720,the indenter 550 can be dimensioned such that the perimeter of theindenter 550 is greater than the perimeter of the cavity 720. Theindenter 550 is oriented so that the first end 650 makes contact withthe cutter 100. Thus, in this embodiment, the PDC layer of the indenter550 makes contact with the PDC layer, or cutter table 120, of the cutter100. The load 580 is applied to the second end 652, which transmits theload 580 onto the cutter 100. Although a dome shaped indenter 550 isused in these exemplary embodiments, other exemplary embodiments can useindenters having other shapes. Also, the second end 652 can be formedinto other non-planar shapes without departing from the scope and spiritof the exemplary embodiments.

The acoustic sensor 570 is a piezoelectric sensor that is positionedalong the coupling portion 730 of the cutter holder 510. However, theacoustic sensor 570 can be any other device type known to people havingordinary skill in the art, wherein the device is capable of detectingacoustic transmissions. The acoustic sensor 570 detects elastic wavesignals formed in the cutter 100, which then converts the elastic wavessignal to a voltage signal so that the data can be recorded andsubsequently analyzed. In certain exemplary embodiments, the lubricant620 is placed at the contact area between the coupling portion 730 andthe acoustic sensor 570. As previously mentioned, the lubricant 620improves detection of elastic wave transmission from the cutter 100 tothe acoustic sensor 570. According to some alternative exemplaryembodiments, the acoustic sensor 570 is sized so that it is capable ofbeing placed on the arcuate portion of the side surface 716. Theacoustic sensor 570 is communicably coupled to the data recorder 590 nothat the voltage signal derived from the elastic waves occurring withinthe cutter 100 can be stored and subsequently analyzed. The acousticsensor 570 is coupled to the data recorder 590 using a cable 592;however, according to other exemplary embodiments, the acoustic sensor570 can be communicably coupled to the data recorder 590 wirelesslyusing wireless technology including, but not limited to, infrared andradio frequency.

The data recorder 590 records the data sent from the acoustic sensor 570and stores the data therein. In certain exemplary embodiments, theapparatus (not shown), or machine, delivering the load 580 also iscoupled to the data recorder 590 using a cable 582; however, accordingto other exemplary embodiments, the apparatus delivering the load 580can be communicably coupled to the data recorder 590 wirelessly usingwireless technology including, but not limited to, infrared and radiofrequency. The data recorder 590 also processes and analyzes the datathat it receives. Although the data recorder 590 records, stores,processes, and analyzes the data, the data recorder 590 can receive thedata, process the data, and analyze the data without storing the dataaccording to some exemplary embodiments. Alternatively, in otherexemplary embodiments, the data recorder 590 can store the data but notprocess or analyze the data. In some exemplary embodiments, anadditional device (not shown) is used to process and analyze the data.

FIG. 10 shows a schematic block diagram of a data recorder 590 of FIG. 5in accordance with an exemplary embodiment. Referring to FIGS. 5 and 10,the data recorder 590 is a computer system. The data recorder 590includes a storage medium 1040, a user interface 1030, a processor 1020,and a display 1010.

The storage medium 1040 receives information from the acoustic sensor570 (FIG. 5) and records the information therein. The storage medium1040 is a hard drive according to one exemplary embodiment. However,according to other exemplary embodiments, the storage medium 1040includes at least one of a hard drive, a portable hard drive, a USBdrive, a DVD, a CD, or any other device capable of storing data and/orsoftware. In some exemplary embodiments, the storage medium 1040 alsoincludes a software for providing instructions on how to process theinformation, or data, received from the acoustic sensor 570 (FIG. 5).

The user interface 1030 allows a user to interface with the datarecorder 590 and provide instructions for operating the data recorder590. According to some exemplary embodiments, the user interfaceincludes a keyboard. However, according to other exemplary embodiments,the user interface includes at least one of a keyboard, a mouse, a touchscreen which can be part of the display 1010, or any other userinterface known to people having ordinary skill in the art.

The processor 1020 is capable of receiving instructions from the userinterface 1030, accessing information stored within the storage medium1040, sending information to the storage medium 1040, and sendinginformation to the display 1010. In some exemplary embodiments, theprocessor 1020 accesses the software that resides within the storagemedium 1040 and executes the set of instructions provided by thesoftware. A more detailed description of these instructions are providedfurther below. In some exemplary embodiments, the processor 1020includes processor engines 2200, which are described in further detailbelow in conjunction with FIGS. 16, 17, 18, and 22.

The display 1010 receives information from the processor andcommunicates this information to the user. According to one exemplaryembodiment, the display 1010 includes a monitor, or screen. However,according to other exemplary embodiments, the display 1010 includes atleast one of a screen, a touch screen, a printer, or any other devicecapable of communicating information to the user.

Although not illustrated in FIG. 10, the data recorder 590 can becommunicably coupled, either wired or wirelessly, to an internalnetwork, wherein the software and/or data from the acoustic sensor 570(FIG. 5) is stored in a central server (not shown). Additionally,according to some alternative exemplary embodiments, the data recorder590 can be communicably coupled, either wired or wirelessly, to a modem(not shown), wherein the modem is communicably coupled to the world wideweb. In certain alternative exemplary embodiments, the software and/ordata from the acoustic sensor 570 (FIG. 5) is stored in a remotelocation that is accessible via the world wide web.

FIG. 8 shows a perspective view of the acoustic emission testing device505 of FIG. 5 with the indenter 550 being removed from the cutter holder510 in accordance with an exemplary embodiment of the present invention.Referring to FIG. 8, the cutter 100 is fully inserted within the cavity720 of the cutter holder 510. As shown, the diameter of the cutter 100is less than the diameter of the cavity 720, thereby forming the airgaps 610. Also, the PDC layer, or the cutter table 120, is orientedwithin the cavity 720 so that the PCD layer faces towards the firstsurface 712. The indenter 550 is removed from the cavity 720 to furtherillustrate some features of the indenter 550. According to thisexemplary embodiment, the indenter 550 includes a substrate 808 and ahard surface 810, which is formed or coupled to the top of the substrate808. In the exemplary embodiment, the hard surface 810 is formed fromPCD, but alternative exemplary embodiments can have the hard surface 810fabricated from other hard or superhard materials, such as PCBN, withoutdeparting from the scope and spirit of the exemplary embodiment.Although indenter 550 has a dome shaped hard surface 810, the hardsurface 810 can be planar or any other shape known to people havingordinary skill in the art. As seen, the indenter 550 has a diametersubstantially similar to the diameter of the cavity 720, according tothis exemplary embodiment.

In an alternative embodiment, the indenter 550 is positioned within thecavity 720 having the hard surface 810 facing towards the first surface712. The cutter 100 to be tested is positioned on top of the indenter550 with the cutter table 120 contacting the hard surface 810. The load580 is applied downward on the back face of the substrate 110 of thetest cutter 100. Acoustic emissions of cracks initiated and/orpropagated in the test cutter 100 is transmitted through the indenter550 and to the acoustic sensor 570. In this alternative exemplaryembodiment, the cutter holder 510 is optional.

FIG. 9 shows a perspective view of an acoustic emission testing system900 in accordance with an alternative exemplary embodiment of thepresent invention. Referring to FIG. 9, the acoustic emission testingsystem 900 includes an acoustic emission testing device 905 communicablycoupled to the data recorder 507. The acoustic emission testing device905 is similar to the acoustic emission testing device 505 of FIG. 5,except that the acoustic sensor 570 is directly coupled to the cutter100 and the cutter holder 510 of FIG. 5 is removed. The cutter 100, theindenter 550, the load 580, the acoustic sensor 570, and the datarecorder 590 have been previously described with respect to FIGS. 5, 6,7, 8, and 10. Also, the lubricant 620 (FIG. 6) is placed between theacoustic sensor 570 and the cutter 100 according to some exemplaryembodiments.

The operation of the acoustic emission testing system 500 is describedwhile referring to FIGS. 5-8. The cutter 100, or hard or superhardmaterial, to be tested is placed within the cavity 720 of the cutterholder 510. To improve the elastic wave transmission across thecontacting surfaces between the base, or bottom surface, of the cutter100 and the base of the cavity 720, a mineral oil based gel 620 is usedbetween the bottom surface of the cutter 100 and the base of the cavity720. The acoustic sensor 570 is positioned against the coupling portion730 of the cutter holder 510 to detect the elastic waves generatedwithin the cutter 100. To improve the elastic wave transmission acrossthe contacting surfaces between the acoustic sensor 570 and the couplingportion 730, the mineral oil based gel 620 also is used between theacoustic sensor 570 and the coupling portion 730. The indenter 550 isplaced on top of the PCD layer 120 of the cutter 100 and is pushedagainst this PCD layer 120 using the load 580. The load 580 is providedon the indenter 550 using a 100 kilonewton 8500 series Instron machine.This machine (not shown) is capable of controlling the amount of loadthat is exerted on the indenter 550. The machine is hooked up to thedata recorder 590 so that load versus time is measured. Although oneexample of a machine capable of providing the load 580 is disclosed, anysystem capable of providing a measurable load to the indenter 550 is inthe scope of exemplary embodiments for this invention. For example, themachine or apparatus for delivering the measurable load 580 can rangefrom a handheld hammer to a fully instrumented impact machine or to aload controlled hydraulic machine for steady ramp or cyclic loadinghistories.

The load 580 is applied onto the indenter 550 and increased at aconstant rate to a desired load level. Once reaching the desired loadlevel, the load level is maintained for a desired period of time, whichcan range from a few seconds to several minutes, and then ramped down ata faster rate than the ramp up rate. Each time a new crack forms or anexisting crack grows within the top diamond layer 120, a certain amountof elastic energy is released almost instantaneously in the form of atrain of elastic waves travelling through the PCD layer 120, thesubstrate 110, and the cutter holder 510. The acoustic sensor 570detects these elastic waves and converts the received signals into avoltage signal. The acoustic sensor 570 is communicably coupled to thedata recorder 590 so that acoustic emissions, or data, are recordedagainst time. These acoustic emissions include background noise andacoustic events. Hence, since the acoustic emissions history and theloading history is recorded onto the data recorder 590, one candetermine at what load 580 certain acoustic events occurred. An acousticevent is an event where a new crack forms or when an existing crackgrows in the PDC layer 120. According to one exemplary embodiment, theacoustic sensor 570 provides data to the data recorder 590 at about5,000 data points per second; however, the data points per second can beincreased or decreased without departing from the scope and spirit ofthe exemplary embodiment.

FIG. 11 shows a graphical cutter acoustic emission and loadingrepresentation 1100 for a cutter experiencing a load of up to about twokilonewtons in accordance with an exemplary embodiment of the presentinvention. Referring to FIG. 11, the cutter acoustic emission andloading representation 1100 includes a time axis 1110, a load axis 1120,and an acoustic emissions axis 1130. The time axis 1110 is representedby an x-axis and is provided with units in the seconds times 5,000.Thus, to obtain the time period in seconds, the numerical value in thetime axis 1110 is to be divided by 5,000. The time axis 1110 can also beread as energy being delivered to the sample. In other words, as moretime passes, more total energy is exerted on the cutter or test sample.The load axis 1120 is represented by a y-axis and is provided with unitsin the kilonewtons. The acoustic emissions axis 1130 also is representedby the y-axis and is provided with units in the millivolts times ten.Thus, to obtain the voltage in millivolts, the numerical value in theacoustic emissions axis 1130 is to be divided by ten. A load curve 1140and an acoustic emissions curve 1160 are both illustrated on the cutteracoustic emission and loading representation 1100. According to the loadcurve 1140, the load was increased from zero kilonewtons to twokilonewtons at a constant rate 1142, or ramp up rate. The load was heldat a peak load level 1143, or two kilonewtons in this example, for aperiod of time and then ramped down at a ramp down rate 1144, which isfaster than the ramp up rate 1142. The acoustic emissions curve 1160represents the recorded signal from the acoustic sensor. According tothe acoustic emissions curve 1160, the only acoustic emissions recordedis a background noise 1162. There were no acoustic events that weredetected. Also, as the load increases, the background noise 1162 alsoincreases.

FIG. 12 shows a graphical cutter acoustic emission and loadingrepresentation 1200 for a cutter experiencing a load of up to about fivekilonewtons in accordance with an exemplary embodiment of the presentinvention. Referring to FIG. 12, the cutter acoustic emission andloading representation 1200 includes a time axis 1210, a load axis 1220,and an acoustic emissions axis 1230. The time axis 1210 is representedby an x-axis and is provided with units in the seconds times 5,000.Thus, to obtain the time period in seconds, the numerical value in thetime axis 1210 is to be divided by 5,000. The time axis 1210 can also beread as energy being delivered to the sample. In other words, as moretime passes, more total energy is exerted on the cutter or test sample.The load axis 1220 is represented by a y-axis and is provided with unitsin the kilonewtons. The acoustic emissions axis 1230 also is representedby the y-axis and is provided with units in the millivolts times ten.Thus, to obtain the voltage in millivolts, the numerical value in theacoustic emissions axis 1230 is to be divided by ten. A load curve 1240and an acoustic emissions curve 1260 are both illustrated on the cutteracoustic emission and loading representation 1200. According to the loadcurve 1240, the load was increased from zero kilonewtons to fivekilonewtons at a constant rate 1242, or ramp up rate. The load was heldat a peak load level 1243, or five kilonewtons in this example, for aperiod of time and then ramped down at a ramp down rate 1244, which isfaster than the ramp up rate 1242. The acoustic emissions curve 1260represents the recorded signal from the acoustic sensor. According tothe acoustic emissions curve 1260, the only acoustic emissions recordedis a background noise 1262. There were no acoustic events that weredetected. Also, as the load increases, the background noise 1262 alsoincreases.

FIG. 13 shows a graphical cutter acoustic emission and loadingrepresentation 1300 for a cutter experiencing a load of up to aboutthirty kilonewtons in accordance with an exemplary embodiment of thepresent invention. Referring to FIG. 13, the cutter acoustic emissionand loading representation 1300 includes a time axis 1310, a load axis1320, and an acoustic emissions axis 1330. The time axis 1310 isrepresented by an x-axis and is provided with units in the seconds times5,000. Thus, to obtain the time period in seconds, the numerical valuein the time axis 1310 is to be divided by 5,000. The time axis 1310 canalso be read as energy being delivered to the sample. In other words, asmore time passes, more total energy is exerted on the sample. The loadaxis 1320 is represented by a y-axis and is provided with units in thekilonewtons. The acoustic emissions axis 1330 also is represented by they-axis and is provided with units in the millivolts times ten. Thus, toobtain the voltage in millivolts, the numerical value in the acousticemissions axis 1330 is to be divided by ten. A load curve 1340 and anacoustic emissions curve 1360 are both illustrated on the cutteracoustic emission and loading representation 1300. According to the loadcurve 1340, the load was increased from zero kilonewtons to thirtykilonewtons at a constant rate 1342, or ramp up rate. The load was heldat a peak load level 1343, or thirty kilonewtons in this example, for aperiod of time and then ramped down at a ramp down rate 1344, which isfaster than the ramp up rate 1342. The acoustic emissions curve 1360represents the recorded signal from the acoustic sensor. According tothe acoustic emissions curve 1360, the acoustic emissions recordedincludes a background noise 1362 and one or more acoustic events 1364.The background noise 1362 makes up the bulk of the data recorded duringthe test. The acoustic events 1364 are shown as thin vertical lines thatsignificantly extend upwards from the background noise 1362. The heightof each acoustic event 1364 above the background noise 1362 isproportional to the amount of elastic energy released by each crackingformation and/or propagation event by means of a calibration constant.Every single acoustic event 1364 lasts on average about fiftymilliseconds. According to this exemplary embodiment, the acousticsensor samples about 5,000 data points per second, which allowsdetection of these acoustic events 1364. Also, as the load increases,the background noise 1362 also increases. After completing this test,the cutter was visually examined. Although there were no visual signs ofany damage on the top PCD surface of the cutter, the acoustic sensor diddetect acoustic events occurring within the cutter. Thus, the acousticsensor is able to detect minimal damage occurring to the cutters onceexposed to a load even though the damage is not visible.

FIG. 14 shows a graphical cutter acoustic emission and loadingrepresentation for a cutter experiencing a load of up to about fortykilonewtons in accordance with an exemplary embodiment of the presentinvention. The same cutter sample used in the tests represented in FIG.13 was used in the test represented in FIG. 14. Referring to FIG. 14,the cutter acoustic emission and loading representation 1400 includes atime axis 1410, a load axis 1420, and an acoustic emissions axis 1430.The time axis 1410 is represented by an x-axis and is provided withunits in the seconds times 5,000. Thus, to obtain the time period inseconds, the numerical value in the time axis 1410 is to be divided by5,000. The time axis 1410 can also be read as energy being delivered tothe sample. In other words, as more time passes, more total energy isexerted on the sample. The load axis 1420 is represented by a y-axis andis provided with units in the kilonewtons. The acoustic emissions axis1430 also is represented by the y-axis and is provided with units in themillivolts times ten. Thus, to obtain the voltage in millivolts, thenumerical value in the acoustic emissions axis 1430 is to be divided byten. A load curve 1440 and an acoustic emissions curve 1460 are bothillustrated on the cutter acoustic emission and loading representation1400. According to the load curve 1440, the load was increased from zerokilonewtons to forty kilonewtons at a constant rate 1442, or ramp uprate. The load was held at a peak load level 1443, or forty kilonewtonsin this example, for a period of time and then ramped down at a rampdown rate 1444, which is faster than the ramp up rate 1442. The acousticemissions curve 1460 represents the recorded signal from the acousticsensor. According to the acoustic emissions curve 1460, the acousticemissions recorded includes a background noise 1462 and one or moreacoustic events 1464. The acoustic events 1464 are shown as verticallines that significantly extend upwards from the background noise 1462.The height of each acoustic event 1464 above the background noise 1462is proportional to the amount of elastic energy released by eachcracking formation and/or propagation event by means of a calibrationconstant. As seen in FIG. 14, acoustic events 1464 did not occur withinthe cutter until the load reached or exceeded the previous load that wasexposed to this cutter. For example, this cutter previously experiencedloads up to thirty kilonewtons as described in FIG. 13. Thus, newacoustic events 1464 did not arise until the load reached and/orexceeded a threshold 1466, which was about thirty kilonewtons in thisexample, that was previously applied on to the cutter. Based upon theexperiments, it seems that to generate new cracks or to grow existingcracks in the cutter that were formed in a previous test run, a loadlevel equal to or higher than the previous peak load level 1343 is to beapplied.

FIG. 15A shows a graphical cutter acoustic emission and loadingrepresentation 1500 for a cutter manufacturer #1 cutter sample #1 cuttertype experiencing a load of up to about forty-five kilonewtons inaccordance with an exemplary embodiment of the present invention. FIG.15B shows a graphical cutter acoustic emission and loadingrepresentation 1550 for a cutter manufacturer #2 cutter sample #2 cuttertype experiencing a load of up to about thirty kilonewtons in accordancewith an exemplary embodiment of the present invention. Referring toFIGS. 15A and 15B, the cutter acoustic emission and loadingrepresentation 1500 includes an acoustic emission curve 1510 showing oneor more acoustic events 1520 occurring within the cutter manufacturer #1cutter sample #1 cutter type, while the cutter acoustic emission andloading representation 1550 includes an acoustic emission curve 1560showing one or more acoustic events 1570 occurring within the cuttermanufacturer #2 cutter sample #2 cutter type. There are significantlymore acoustics events 1520 and 1570 occurring within the cuttermanufacturer #2 cutter sample #2 cutter type than in the cuttermanufacturer #1 cutter sample #1 cutter type. Thus, different cuttertypes show different acoustic patterns within their respective acousticemissions curve. Based upon these results, a user can determine whichcutter type is tougher than another cutter type and can thereby rankcutters according to their toughness. In this case, the cuttermanufacturer #1 cutter sample #1 cutter type is tougher than the cuttermanufacturer #2 cutter sample #2 cutter type.

Based upon the experimental results shown in FIGS. 11-15, there are atleast several observations that can be made. First, the acoustic sensoris able to detect crack formation and crack growth within the diamondtable of the cutter as the indenter is being loaded and is able to sendsignals that are subsequently analyzable. Second, different cutter typesshow different acoustic event patterns and allow a user to rank thetoughness of the cutter when compared to another cutter. Third, althoughthere can be no visible damage that is detectable on the surface of thePDC table of the cutter after the test, the acoustic sensor is able todetect any non-visible damage occurring to the cutter.

FIG. 16 illustrates a flowchart of a method 1600 for analyzing datapoints received from the acoustic sensor, wherein the method includes aloop one method 1680 and a loop two method 1690 in accordance with anexemplary embodiment of the present invention. Although certain stepsare shown as proceeding in a particular order, the sequence of steps canbe varied without departing from the scope and spirit of the exemplaryembodiment. Also, although certain functions are performed in one ormore steps, the number of steps for performing that function can beincreased or decreased without departing from the scope and spirit ofthe exemplary embodiment.

Referring to FIG. 16, at step 1605, the method 1600 starts. From step1605, method 1600 proceed to step 1610. At step 1610, one or moreminimum threshold values above the background noise to qualify a datapoint as a possible acoustic event is determined. Upon completion ofstep 1610, method 1600 proceeds to step 1615 and step 1625, which canoccur simultaneously in certain exemplary embodiments. At step 1615, thebackground points delimiting the outer envelop of the background noiseis determined. At step 1625, the possible acoustic event points isdetermined based upon the one or more threshold values determined atstep 1610. Step 1615 and step 1625 are included in the loop one method1680, which is described in further detail below in conjunction withFIG. 17.

From step 1615, method 1600 proceeds to step 1620. At step 1620, thebackground points determined at step 1615 are interpolated to produce abackground noise function curve. From steps 1620 and 1625, method 1600proceeds to step 1630. At step 1630, actual acoustic event points aredetermined using the possible acoustic event points determined at step1680 and the background noise function curve determined at step 1620.From step 1630, method 1600 proceeds to step 1635. At step 1635, theamplitude and duration of each actual acoustic event point isdetermined. From step 1635, method 1600 proceeds to step 1640. At step1640, the area under each acoustic event point is calculated. From step1640, method 1600 proceeds to step 1645. At step 1645, the cumulativedistribution of the areas is compared to the actual test load for eachacoustic event point. A user can use this comparison to make adetermination as to the relative toughness of one cutter to anothercutter. This comparison allows the determination to be made using aquantitative and objective methods. The duration, amplitude, andfrequency of the acoustic event points and the corresponding level ofenergy, or load, delivered to the sample can be correlated directly withthe field impact performance of the PCD, or other hard or superhardmaterial, being tested. Method 1600 allows measurement of not only thesmallest amount of external work, or load, required to initiate somedamage but also allows measurement of the amount of additional work, orload, that has to be done to increase the damage level. After step 1645,method 1600 proceed to step 1650 where method 1600 is stopped.

FIG. 19 shows a graphical cutter acoustic emission representation 1900for a cutter experiencing a load in accordance with an exemplaryembodiment of the present invention. FIG. 20 shows a magnified view of aportion of a graphical cutter acoustic emission representation 2000 fora cutter experiencing a load in accordance with an exemplary embodimentof the present invention. FIG. 21 shows a cumulative distributionrepresentation 2100 for each actual acoustic event in accordance with anexemplary embodiment of the present invention. FIGS. 19-21 depict amajority of the steps illustrated in method 1600 of FIG. 16.

Referring to FIG. 19, the cutter acoustic emission representation 1900includes a time axis 1910 and an acoustic emissions axis 1930. The timeaxis 1910 is represented by an x-axis and is provided with units in theseconds times 5,000. Thus, to obtain the time period in seconds, thenumerical value in the time axis 1910 is to be divided by 5,000. Theacoustic emissions axis 1930 is represented by a y-axis and is providedwith units in the millivolts time ten. Thus, to obtain the voltage inmillivolts, the numerical value in the acoustic emissions axis 1930 isto be divided by ten. An acoustic emissions data 1960 is illustrated onthe cutter acoustic emission representation 1900. The acoustic emissionsdata 1960 represents the recorded signal from the acoustic sensor.According to the acoustic emissions data 1960, the acoustic emissionsdata recorded includes one or more background points 1962 and one ormore possible acoustic event points 1964. Referring to FIGS. 16 and 19and according to step 1615 and step 1625 of FIG. 16, the acousticemissions data 1960 is sorted to include background points 1962 andpossible acoustic event points 1964. The sorting of the acousticemissions data 1960 is performed using an algorithm that resides withindata recorder 590 (FIG. 5) according to one exemplary embodiment.However, the algorithm can be stored in another device in alternativeexemplary embodiments or is performed manually. Alternatively, othermethods known to people having ordinary skill in the art and having thebenefit of the present disclosure can be used to categorize the acousticemissions data 1960. As shown in FIG. 19, each background point 1962 ismarked with a circle and each possible acoustic event point 1964 ismarked with a square. There are some points that are not defined aseither a background point 1962 or a possible acoustic event point 1964.These markings are for illustrative purposes and is not meant to limitthe scope of exemplary embodiments of the present invention.

Referring to FIGS. 16 and 19 and according to step 1620 of FIG. 16, abackground noise function curve 1970 is interpolated using thedetermined background points 1962. According to one exemplaryembodiment, the background noise function curve 1970 is interpolatedusing a fourth degree polynomial; however, other degrees of polynomialcan be used to interpolate the background points 1962 without departingfrom the scope and spirit of the exemplary embodiment.

Referring to FIG. 20, a magnified portion of the graphical cutteracoustic emission representation 2000 is presented. According to thisfigure, each acoustic emissions data 1960, which includes the actualacoustic event points 2010, has a time duration 2020 that it occurs in.Additionally, each actual acoustic event point 2010, has an amplitude2030 that is measured vertically from the background noise functioncurve 1970 to the position where the actual acoustic event point 2010lies. Referring to FIGS. 16 and 20 and according to step 1635 of FIG.16, the amplitude 2030 and the time duration 2020 of the actual acousticevent point 2010 is calculated. Once the amplitude 2030 and the timeduration 2020 is determined, the area 2040 under each actual acousticevent point 2010 is calculated by multiplying the amplitude 2030 to thetime duration 2020. This step is accomplished in step 1640 of FIG. 16.According to some of the exemplary embodiments, the units for the area2040 is millivolt times seconds times 5,000; however, other units can beused without departing from the scope and spirit of the exemplaryembodiment.

Referring to FIG. 21, a cumulative distribution representation 2100 foreach actual acoustic event is presented. According to this figure, thecumulative distribution representation 2100 includes a load axis 2110and an acoustic emissions area axis 2130. The load axis 2110 isrepresented by an x-axis and is provided with units in the kilonewtons.The acoustic emissions area axis 2130 is represented by a y-axis and isprovided with units in the millivolts times seconds times fiftythousand. This is the area that is determined that lies under an actualacoustic event point. Thus, to obtain the area in millivolts timesseconds, the numerical value in the acoustic emissions area axis 2130 isto be divided by fifty thousand. Referring to FIGS. 16 and 21 andaccording to step 1645 of FIG. 16, the cumulative distribution of theareas, which is plotted along the acoustic emissions area axis 2130, iscompared to the actual test load, which is plotted along the load axis2110, for each actual acoustic event. The cumulative distributionrepresentation 2100 provides these comparisons for a cutter manufacturer#1 cutter sample #1 cutter plot 2150 and a cutter manufacturer #2 cuttersample #2 cutter plot 2160.

For example, in one of the three cutter manufacturer #1 cutter sample #1cutter plots 2150, there is an actual acoustic event point at abouttwenty-eight kilonewtons and at about 3550 millivolt times seconds times50,000, which is labeled as a Point A 2152. This means that there hasbeen a cumulative area of 3550 millivolt times seconds times 50,000which has occurred under all previous actual acoustic event points,including the area for the actual acoustic event point that occurred atabout a load of about twenty-eight kilonewtons. The next actual acousticevent point, Point B 2154, on that same curve occurs at about 32.5kilonewtons. The area under that actual acoustic event point is about650 millivolt times seconds times 50,000, which is not directly shown onthe cumulative distribution representation 2100. However, at about 32.5kilonewtons, there has been a cumulative area of about 4200 millivolttimes seconds times 50,000. Thus, about 4200 millivolt times secondstimes 50,000 minus about 3550 millivolt times seconds times 50,000 isequal to about 650 millivolt times seconds times 50,000. The hardercutter, or the one that is more intrinsically tougher, provides a curvethat has a less cumulative area for a given load. A cutter with a steepcurve with a lot of high amplitude actual acoustic event points is lessintrinsically tougher than a cutter with a less steep curve and fewerhigh amplitudes actual acoustic event points. Thus, according to thecumulative distribution representation 2100, a comparison between thecutter manufacturer #1 cutter sample #1 cutter plot 2150 and the cuttermanufacturer #2 cutter sample #2 cutter plot 2160 indicates that thecutter manufacturer #1 cutter sample #1 cutter is intrinsically tougherthan the cutter manufacturer #2 cutter sample #2 cutter. Also, accordingto FIG. 21, there are three curves that represent the cuttermanufacturer #1 cutter sample #1 cutter plot 2150 and two curves thatrepresent the cutter manufacturer #2 cutter sample #2 cutter plot 2160.These plots 2150 and 2160 illustrate that method 1600 (FIG. 16) has ahigh resolution so that variabilities within samples of the same groupare detectable. The method provided in FIG. 16 provides information to auser for ranking cutter toughnesses amongst other cutters in anobjective manner.

FIG. 17 illustrates a detailed flowchart of the loop one method 1680 ofFIG. 16 in accordance with an exemplary embodiment of the presentinvention. Referring to FIG. 17, at step 1705, the loop one method 1680starts. From step 1705, loop one method 1680 proceeds to step 1710. Atstep 1710, the first data point is read. Upon completion of step 1710,loop one method 1680 proceeds to step 1715, where the next data point isread. After step 1715, loop one method 1680 proceeds to step 1720. Atstep 1720, the difference between the two data points is calculated andcompared to a first tolerance value that is used to define an acousticevent. According to one exemplary embodiment, the first tolerance valueis about 0.5 millivolts. However, the first tolerance value can behigher or lower in other exemplary embodiments. If the differencebetween the two data points is not less than the first tolerance value,loop one method 1680 proceeds to step 1725. At step 1725, the second ofthe two data points is defined as a possible acoustic event point. Fromstep 1725, loop one method 1680 proceeds to step 1745, where loop onemethod 1680 determines whether there is another data point. If at step1745, it is determined that there is not another data point, loop onemethod 1680 proceeds to step 1750, where the loop one method 1680 stops.However, if at step 1745, it is determined that there is another datapoint, the loop one method 1680 proceeds back to step 1715.

If at step 1720, it is determined that the difference between the twodata points is less than the first tolerance value, the loop one method1680 proceeds to step 1730. At step 1730, the difference between the twodata points is compared to a second tolerance value. According to oneexemplary embodiment, the second tolerance value is about 0.01millivolts. However, the second tolerance value can be higher or lowerin other exemplary embodiments. If the difference between the two datapoints is not less than the second tolerance value, loop one method 1680proceeds back to step 1715 and the second data point is not defined.However, if the difference between the two data points is less than thesecond tolerance value, loop one method 1680 proceeds to step 1735.

At step 1735, it is determined whether the difference between the twodata points is negative and has been negative for less than “z” times ina row or whether the difference is positive and has been positive forless than “u” times in a row. According to one exemplary embodiment, the“z” is two and the “u” is three. However, either or both the “u” valueand the “z” value can be higher or lower in other exemplary embodiments.If it is not true that the difference between the two data points isnegative and has been negative for less than “z” times in a row or ispositive and has been positive for less than “u” times in a row, thenthe loop one method 1680 proceeds back to step 1715 and the second datapoint is not defined. However, if the difference between the two datapoints is negative and has been negative for less than “z” times in arow or is positive and has been positive for less than “u” times in arow, then the loop one method 1680 proceeds to step 1740.

At step 1740, the second of the two data points is defined as abackground boundary point. From step 1740, the loop one method 1680proceeds to step 1745, where it is determined whether there is anotherdata point. The loop one method 1680 continues until step 1750 isreached pursuant to the steps described above. Thus, the loop one method1680 provides a method for determining which data points should bedefined as a possible acoustic event point, a background boundary point,or not defined as either type of point.

FIG. 18 illustrates a detailed flowchart of the loop two method 1690 ofFIG. 16 in accordance with an exemplary embodiment of the presentinvention. Referring to FIG. 18, at step 1805, the loop two method 1690starts. From step 1805, loop two method 1690 proceeds to step 1810. Atstep 1810, a background noise function curve is created using thebackground boundary points. Upon completion of step 1810, loop twomethod 1690 proceeds to step 1815, where the first possible acousticevent point is read. After step 1815, loop two method 1690 proceeds tostep 1820. At step 1820, the difference between the possible acousticevent point and the background noise function curve is calculated anddetermined whether this difference is greater than a third tolerancevalue that is used to define an actual acoustic event point. Accordingto one exemplary embodiment, the third tolerance value is about 0.08millivolts. However, the third tolerance value can be higher or lower inother exemplary embodiments. If the difference between the possibleacoustic event point and the background noise function curve is notgreater than the third tolerance value, loop two method 1690 proceeds tostep 1825. At step 1825, the next possible acoustic event point is readand the loop two method 1690 proceeds back to step 1820. However, if thedifference between the possible acoustic event point and the backgroundnoise function curve is greater than the third tolerance value, loop twomethod 1690 proceeds to step 1830.

At step 1830, the amplitude, the duration, and the area between theactual acoustic event point and the background noise function curve arecalculated From step 1830, the loop two method 1690 proceeds to step1840. At step 1840, it is determined whether there is another possibleacoustic event point. If there is another possible acoustic event point,the loop two method 1690 proceeds back to step 1825, where the loop twomethod 1690 continues. However, at step 1840, if there is not anotherpossible acoustic event point, the loop two method 1690 proceeds to step1845, where the loop two method 1690 stops. Thus, the loop two method1690 provides a method for determining which data points should bedefined as an actual acoustic event point and then calculates the areafor each defined acoustic event point.

FIG. 22 illustrates a block diagram of the processor 1020 of FIG. 10 inaccordance with an exemplary embodiment. As previously mentioned, themethod for performing one or more steps illustrated in FIGS. 16-18 isperformed within the processor 1020. However, in certain other exemplaryembodiments, these methods are performed manually or a combination ofmanually and within a processor. The processor 1020 is located withinthe data recorder 590, or a computer system. Although one processor 1020is shown, multiple processors can be used without departing from thescope and spirit of the exemplary embodiments. Processor 1020 includesone or more processor engines 2200.

The processor engines 2200 include an acoustic data gathering engine2210, a background points determination engine 2220, a possible acousticevent points determination engine 2230, a background noise functioncurve interpolation engine 2240, an actual acoustic event pointsdetermination engine 2250, an actual acoustic event area calculationengine 2260, and a cumulative area and load curve engine 2270. Althoughseven engines are included within the processor engines 2200, the numberof engines can be greater or fewer in other exemplary embodiments.Additionally, one or more of these previously mentioned processorengines 2200 can be combined into fewer processor engines 2200 orseparated into additional processor engines 2200 without departing fromthe scope and spirit of the exemplary embodiments.

The acoustic data gathering engine 2210 gathers data from at least theacoustic sensor, which includes background points and possible acousticevent points. The acoustic data gathering engine 2210 also gathers datafrom the load, in some exemplary embodiments, so that correspondingbackground points and possible acoustic event points are related to agiven load. The background points determination engine 2220 evaluatesthe data obtained from the acoustic sensor and determines whether thedata point is a background point. The background points determinationengine 2220 performs step 1615 of FIG. 16. The possible acoustic eventpoints determination engine 2230 evaluates the data obtained from theacoustic sensor and determines whether the data point is a possibleacoustic event point. The possible acoustic event points determinationengine 2230 performs step 1625 of FIG. 16. The background pointsdetermination engine 2220 and the possible acoustic event pointsdetermination engine 2230 run simultaneously with one another, but canrun independently from one another in some alternative exemplaryembodiments.

The background noise function curve interpolation engine 2240 generatesa background noise function curve using the background points that werepreviously determined. The background noise function curve interpolationengine 2240 performs step 1620 of FIG. 16. The actual acoustic eventpoints determination engine 2250 determines actual acoustic event pointsusing the possible acoustic event points that were previously determinedand the background noise function curve. The actual acoustic eventpoints determination engine 2250 performs step 1630 of FIG. 16. Once theactual acoustic event points are determined, the actual acoustic eventarea calculation engine 2260 determines the area formed between theactual acoustic event point and the background noise function curve. Theactual acoustic event area calculation engine 2260 performs step 1635and step 1640 of FIG. 16. The cumulative area and load curve engine 2270compares the cumulative distribution of the areas to the actual testload for each actual acoustic event point. The cumulative area and loadcurve engine 2270 performs step 1645 of FIG. 16. Although the processorengines 2200 are located in the processor 1020 in some exemplaryembodiments, the processor engines 2200 can reside in a storage mediumincluding, but not limited to, one or more hard drives, a USB drive, acompact disc, a digital video disc, or any other storage device known ornot yet known to people having ordinary skill in the art.

Although processor engines 2200 are described in the exemplaryembodiments, the instructions for determining the toughness of thecutter can be provided in a software that resides within the storagemedium 1040 (FIG. 10). The software includes modules and/or code thatare similar to the processor engines 2200 described above.

Although some exemplary embodiments of the invention have beendescribed, alternative exemplary embodiments include the use of heatingthe hard or superhard component 100. This heating of the hard orsuperhard component 100 occurs at either or a combination of before,during, and/or after the application of the load onto the hard orsuperhard component 100. The heat is supplied in any one of a number ofways known to people having ordinary skill in the art, which include,but is not limited to, flame, laser, infrared, and/or heated liquid.

Although each exemplary embodiment has been described in detail, it isto be construed that any features and modifications that are applicableto one embodiment are also applicable to the other embodiments.Furthermore, although the invention has been described with reference tospecific embodiments, these descriptions are not meant to be construedin a limiting sense. Various modifications of the disclosed embodiments,as well as alternative embodiments of the invention will become apparentto persons of ordinary skill in the art upon reference to thedescription of the exemplary embodiments. It should be appreciated bythose of ordinary skill in the art that the conception and the specificembodiments disclosed may be readily utilized as a basis for modifyingor designing other structures or methods for carrying out the samepurposes of the invention. It should also be realized by those ofordinary skill in the art that such equivalent constructions do notdepart from the spirit and scope of the invention as set forth in theappended claims. It is therefore, contemplated that the claims willcover any such modifications or embodiments that fall within the scopeof the invention.

What is claimed is:
 1. A method for determining the toughness of atesting sample, the method comprising the steps of: providing anacoustic emission testing device, comprising: the testing samplecomprising a hard surface; an acoustic sensor coupled to the testingsample; a cavity receiving the testing sample; and an indenterreleasably coupled to the hard surface, the indenter being tougher thanthe hard surface; inserting the indenter into the cavity, therebyexerting a load onto the hard surface, the load being varied whensubjected onto the testing sample; gathering acoustic data with theacoustic sensor resulting from the load applied to the testing sample;determining one or more background points; determining one or morepossible acoustic event points; interpolating a background noisefunction curve using the one or more background points; determining oneor more actual acoustic event points using the possible acoustic eventpoints and the background noise function curve; and calculating one ormore acoustic event areas bounded between the actual acoustic eventpoints and the background noise function curve, wherein the testingsample is damaged when the load is subjected onto the testing sample andgenerates the one or more actual acoustic event points.
 2. The method ofclaim 1, wherein the steps of determining the one or more backgroundpoints and determining the one or more possible acoustic event pointsare performed concurrently.
 3. The method of claim 2, wherein eachbackground point is determined when the difference between twosequential data points is less than a first threshold and wherein eachpossible acoustic event point is determined when the difference betweentwo sequential data points is greater than the first threshold.
 4. Themethod of claim 3, wherein the first threshold is 0.05 millivolts. 5.The method of claim 2, wherein each background point is determined whenthe difference between two sequential data points is less than a secondthreshold and wherein each possible acoustic event point is determinedwhen the difference between two sequential data points is greater than afirst threshold.
 6. The method of claim 5, wherein the first thresholdis 0.05 millivolts and the second threshold is 0.01 millivolts.
 7. Themethod of claim 2, wherein each background point is determined when thedifference between two sequential data points is less than a secondthreshold and is negative and has been negative for less than “z” timesin a row or when the difference between two sequential data points isless than the second threshold and is positive and has been positive forless than “u” times in a row and wherein each possible acoustic eventpoint is determined when the difference between two sequential datapoints is greater than a first threshold.
 8. The method of claim 7,wherein the first threshold is 0.05 millivolts, the second threshold is0.01 millivolts, the “z” is two, and the “u” is three.
 9. The method ofclaim 1, wherein each actual acoustic event point is determined when thedifference between the respective possible acoustic event point and thebackground noise function curve is greater than a third threshold. 10.The method of claim 9, wherein the third threshold is 0.08 millivolts.11. The method of claim 1, wherein each acoustic event area iscalculated by multiplying an amplitude of the respective actual acousticevent point from the background noise function curve to a time durationof the respective actual acoustic event point.
 12. The method of claim11, further comprising generating a cumulative area and load curve usinga cumulative area bounded between the actual acoustic event points andthe background noise function curve.
 13. The method of claim 12, whereinthe cumulative area and load curve is generated by plotting each actualacoustic event point using the respective load thereof and thecumulative area thereof, wherein the cumulative area comprises a totalof the event area thereof and the event areas of all previous actualacoustic points.
 14. The method of claim 12, wherein a user objectivelydetermines a toughness for the testing sample using the cumulative areaand load curve.
 15. The method of claim 1, further comprising heatingthe testing sample.
 16. The method of claim 1, wherein: the testingsample comprises a cutter, the hard surface is a superhard cutting tablecoupled to a substrate, and the actual acoustic event points are theinitiation or propagation of cracks in the cutting table.
 17. A systemand computer program product for determining the toughness of a testingsample, the system and computer program product, comprising: the systemcomprising: the testing sample comprising a hard surface; an acousticsensor acoustically coupled to the testing sample; a cavity receivingthe testing sample; an indenter releasably coupled to the hard surface,the indenter being tougher than the hard surface and configured to applya load to the testing sample; and a machine for inserting the indenterinto the cavity, thereby exerting a load onto the hard surface, the loadbeing varied when subjected onto the testing sample; the computerprogram product comprising: a non-transitory computer-readable mediumcontaining computer instructions stored therein, comprising:computer-executable program code for gathering acoustic data with theacoustic sensor resulting from the load applied to the testing sample,the acoustic sensor being communicably coupled to the testing sample,the load being varied when subjected onto the testing sample;computer-executable program code for determining one or more backgroundpoints; computer-executable program code for determining one or morepossible acoustic event points; computer-executable program code forinterpolating a background noise function curve using the backgroundpoints; computer-executable program code for determining one or moreactual acoustic event points using the possible acoustic event pointsand the background noise function curve; and computer-executable programcode for calculating one or more acoustic event areas bounded betweenthe actual acoustic event points and the background noise functioncurve, wherein the testing sample is damaged when the load is subjectedonto the testing sample and generates the one or more actual acousticevent points.
 18. The system and computer program product of claim 17,wherein the computer-executable program code for determining one or morebackground points and the computer-executable program code fordetermining one or more possible acoustic event points are performedconcurrently.
 19. The system and computer program product of claim 18,wherein each background point is determined when the difference betweentwo sequential data points is less than a second threshold and whereineach possible acoustic event point is determined when the differencebetween two sequential data points is greater than a first threshold.20. The system and computer program product of claim 19, wherein thefirst threshold is 0.05 millivolts and the second threshold is 0.01millivolts.
 21. The system and computer program product of claim 17,wherein each actual acoustic event point is determined when thedifference between the respective possible acoustic event point and thebackground noise function curve is greater than a third threshold. 22.The system and computer program product of claim 21, wherein the thirdthreshold is 0.08 millivolts.
 23. The system and computer programproduct of claim 17, wherein each acoustic event area is calculated bymultiplying an amplitude of the respective actual acoustic event pointfrom the background noise function curve to a time duration of therespective actual acoustic event point.
 24. The system and computerprogram product of claim 23, wherein the computer-readable mediumfurther comprises computer-executable program code for generating acumulative area and load curve using a cumulative area bounded betweenthe actual acoustic event points and the background noise functioncurve.
 25. The system and computer program product of claim 24, whereinthe cumulative area and load curve is generated by plotting each actualacoustic event point using the respective load thereof and thecumulative area thereof, wherein the cumulative area comprises a totalof the event area thereof and the event areas of all previous actualacoustic points.
 26. The system and computer program product of claim17, wherein: the testing sample comprises a cutter, the hard surface isa superhard cutting table coupled to a substrate, and the actualacoustic event points are the initiation or propagation of cracks in thecutting table.
 27. A system for determining the toughness of a testingsample, the system comprising: an acoustic emission testing device,comprising: the testing sample comprising a hard surface; a sensorcoupled to the testing sample; an indenter configured to exert a varyingload onto the hard surface, the indenter being tougher than the hardsurface; a cavity receiving the testing sample; and a machine forinserting the indenter into the cavity, thereby exerting a load onto thehard surface, the load being varied when subjected onto the testingsample; an acoustic data gathering module for gathering acoustic datafrom the sensor resulting from the load applied to the testing sample; abackground points determination module for determining one or morebackground points; a possible acoustic event points determination modulefor determining one or more possible acoustic event points; a backgroundnoise function curve interpolation module for interpolating a backgroundnoise function curve using the background points; an actual acousticevent points determination module for determining one or more actualacoustic event points using the possible acoustic event points and thebackground noise function curve; and an actual acoustic event areacalculation module for calculating one or more acoustic event areasbounded between the actual acoustic event points and the backgroundnoise function curve, wherein the testing sample is damaged when theload is subjected onto the testing sample and generates the one or moreactual acoustic event points.
 28. The system of claim 27, wherein eachbackground point is determined when the difference between twosequential data points is less than a first threshold and wherein eachpossible acoustic event point is determined when the difference betweentwo sequential data points is greater than the first threshold.
 29. Thesystem of claim 27, wherein each actual acoustic event point isdetermined when the difference between the respective possible acousticevent point and the background noise function curve is greater than athird threshold.
 30. The system of claim 27, wherein each acoustic eventarea is calculated by multiplying an amplitude of the respective actualacoustic event point from the background noise function curve to a timeduration of the respective actual acoustic event point.
 31. The systemof claim 27, further comprising a cumulative area and load curve modulefor generating a cumulative area and load curve using a cumulative areabounded between the actual acoustic event points and the backgroundnoise function curve.
 32. The system of claim 27, wherein: the testingsample comprises a cutter, and the hard surface is a superhard cuttingtable coupled to a substrate, and the actual acoustic event points arethe initiation or propagation of cracks in the cutting table.